Can anyone tell me what this is

[Irishspring46]

I think it’s an 8.5 10 bolt I was told it is a grand national rear end??

 

[Rktpwrd]

I think it’s an 8.5 10 bolt I was told it is a grand national rear end?? View attachment 238906

That is indeed an 8.5” 10 bolt rear end. The squared off triangles at the bottom are the dead giveaway, 7.5” rears have what look like curved “fangs” there. It could be GN, but it could also be from an Olds 442.

 

[Irishspring46]

That is indeed an 8.5” 10 bolt rear end. The squared off triangles at the bottom are the dead giveaway, 7.5” rears have what look like curved “fangs” there. It could be GN, but it could also be from an Olds 442.

Thanks these came with 342 gears and 373?

 

[Rktpwrd]

Thanks these came with 342 gears and 373?

Correct. Not all came with the G80 PosiTraction option though, so be aware of that if making a decision on it. Do your due diligence.

 

[69hurstolds]

3.42 came in the GNs.

3.73 came in the 84 H/O and 85-87 442s. (83 H/Os had 3.73 but had a 7.5.)

Of course, you could swap them out to whatever gear ratio you wanted.

 

[Irishspring46]

3.42 came in the GNs.

3.73 came in the 84 H/O and 85-87 442s. (83 H/Os had 3.73 but had a 7.5.)

Of course, you could swap them out to whatever gear ratio you wanted.

Thx much appreciated👍

 

[GP403]

Thanks to those who took the time to help the OP out. I would eat off of that rear end.

Quick aside: Do you know *why* "Google is your friend?" Because of people helpfully answering questions and sharing experience and information on the internet. 🤔 It's true.

Carry on!

 

[ssn696]

If the hen's tooth you find is a non-posi, that's a bargaining point, and you can upgrade to a 30-spline 8.5/8.6 GM truck differential and upgraded Moser GN axles to match.

A103004 - 10 Bolt 30 spline C-Clip Axles - Fits 1984-88 Buick Grand National, Olds Hurst - Moser Engineering

A103004 - 10 Bolt 30 spline C-Clip Axles - Fits 1984-88 Buick Grand National, Olds Hurst PRODUCT DESCRIPTIONPart #: A103004Quantity: 2 AxlesMfg: GMModel: Buick Grand National, Olds HurstYear: 1982-1987Rear End: 10-Bolt ChevySpline Count: 30Length: 28 7/16" long, Bolt Pattern(s): (2) 5 x 4 3/4TAP...

www.moserengineering.com

 

[Ribbedroof]

Devil's advocate time

It does in fact appear to be an 8.5 rear center section

The 8.5 rear was used in a lot of applications over the years. There have been a few that were swapped into G bodies from other vehicles. Some done well, some not. None would be a direct swap, aside from the aformentioned G body models.

I would ensure that it is the correct housing before I would start negotiating on it. Chances are it's the real deal, but you need to go into it eyes open

 

[Irishspring46]

Devil's advocate time

It does in fact appear to be an 8.5 rear center section

The 8.5 rear was used in a lot of applications over the years. There have been a few that were swapped into G bodies from other vehicles. Some done well, some not. None would be a direct swap, aside from the aformentioned G body models.

I would ensure that it is the correct housing before I would start negotiating on it. Chances are it's the real deal, but you need to go into it eyes open

How would you determine if it was done well or not? Just by how it functions/rides?